Radiotelegraphy



Oct. 23 1923. 1,471,406

F. S. M CULLOUGH RADIOTELEGRAPHY Filed July 25 1919 4 Sheets-Sheet 1 BxWM W HTTaR/VEYJ.

Oct. 23, 1923. 1,471,406

F. s. MCCULLOUGH RADIOTELEGRAPHY Filed July 25 1919 4 Sheets-Sheet 2 1"L24 nnmmygl; W

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Oct. 23 1923. 1,471,406

F. s. MOCULLOUGH RADIOTELEGRAPHY Filed July 25 1919 4 Sheets-Sheet 4l/vl/awroe: 3 M 4? AW 5 TM 71.4161 1 I. 14 770195X:

Patented a. is, 1923.

UNITED STATES PATENT OFFICE.

FREDERICK S. KOOULLOUGH, OF CLEVELAND, OHIO, ASSIGNOB TO GLENN L.MARTIN, OF CLEVELAND, OHIO.

RADIOTELEGRAPHY Application filed July 25, 1919. Serial No. 813,181.

To all whom it may concern:

Be it known that I, FREDERICK S. MOCUL- LOUGH, a citizen of the UnitedStates, resident of Cleveland, county of Cuyahoga, and

State of Ohio, have invented new and useful Improvements inRadiotelegraphy, which the following is a specification, the principleof the invention beingherein explained and the best mode in which I havecontemplated applying that principle, so as to distinguish it from otherinventions.

My invention relates to systems of radio telegraphy and moreparticularly to systems for determining the direction of distanttransmitting stations. 1

In the radio directional systems hitherto employed, the incomingelectromagnetic waves have been received on antennae having specialforms. generally in the shape of a closed loop, and the strength of thesignals, with whatever form of detector that has been used, has beendetermined by the loudness of the sounds received in a tele phone. Thisaudible means of determining the direction of incoming radiant energy ismore or less indefinite under any circumstances, and fails altogetherwhere there are loud extraneous noises, as, for instance, on anaeroplane.

In view of these considerations, I have invented a system by which thestrength of the received signals is shown visually, and the direction ofmaximum or minimum effect of the received electromagnetic waves, andhence the direction of the transmitting station, can be determined withgreat accuracy, and in spite of any amount of noise in the vicinity.

My invention also makes it easy to determine the direction of two ormore distant transmitting stations simultaneously, and to determine theposition of a moving receiving station, such as that on an aircraft or aboat, at any moment. The annexed drawings and the following descriptionset forth in detail certain means embodying my invention, the disclosedmeans, however, constituting but one of various mechanical forms inwhich the principle of the invention may be employed.

In the accompanying drawings, which are largely diagrammatical, Figure 1shows one form of my radio directional apparatus with a cathode-ray-tubeindicating means.

j F igure. 3 shows another modification of my invention, having areceiving antenna with a large loop, with a crystal detector and acathode-ray tube.

Figure 4 shows a modification of my system, with means for amplifyingthe received osgillations, and with a sensitive galvanome r.

Figure 5 shows a modification of my system with a 100 antenna, means foramplifying the received oscillations, and a galvanometer.

Figure 6 shows a modified form of my system, with two directional loopantennae.

Figure 7 shows a modification of my system, with two directional tubeunits.

Figure 8 shows a modified form of my invention for determining thedirection of two transmitting stations simultaneously.

Figure 9 shows, diagrammatically, a method for determining theinstantaneous position of a moving body, such as an aircraft or boat.

Figure 10 shows a modified form of my invention for determining thedirection of three transmitting stations simultaneously.

In Figure 1, l is a cathode-ray tube; 2

.is an induction or spark coil: 3 is a cathode,

and 4; is an anode, both inside the tube and connected with the sparkcoil; rays are iven oil by the cathode, and are interce ted y thediaphragm 5, which p'ermits only a beam or pencil of rays to passthrough a small opening; 6 is a surface, such as a mica screen orotherfluorescent surface, on which the beam of cathode rays impinges,making a bright spot when the beam is steady, and tracing a line oflight when the beam moves. This screen is preferably transparent ortranslucent, so that the spot or line of light is visible on eitherside. This screen may have a scale marked on it, to

measure the line of light. 7 and 8 are electrodes inside the tube andconnected with the radio directional system; 9 and 10 are positions ofthe beam of cathode rays under the influence of electrodes 7 and 8; 11is an evacuated tube; 12 is a directional coil inside the evacuatedtube; 13 is another directional coil inductively related to coil 12,with its axis parallel to, or coincident with that of 12, and alsocontained in the evacuated tube; 14 is a heated filament, or othersource of ionization, also contained in the evacuated tube; 1:") is avariable condenser crmneet'ed with coils 12 and l3; 1G is a variablecondenser connected with coil 13 and tian'ent 14; l i a batter v for heaing lilament 14; 18 is a variable rcsistance; and 19 is a batterv forenergizing'the circuit containing the filament 14, coil 12 and theelectrodes 7 and 8. 20 is a mirror, which refleets the spot or line oflight from the surface or screen 6 to a scale 21, the line of light onthe scale being shown at 22.

In Figure 1/1, (3 is an end view of the screen in the cathode-ray tube,on which-is shown a line of light, 23, formed when the beam of raysmoves.

In .Figure 2, 1 to 10, inclusive, are elements similar to those havingthe same numbers in Figure 1; 24 is a closed loop antenna; 25 is avariable inductance; and 2G is a variable condenser. The loop shouldhave such characteristics and the electrical quantities of the circuitsshould have such values as Will give the best results in each case. 27is a filament; 28 is a grid and 29 is a plate, all three contained in avacuum tube 30. 31 is the battery for the plate circuit; 32. is thebattery for heating the filament 27; and is a variable resistance in thefilament circuit.

In Figure 3, 1 to 10, inclusive, are elements similar to those havingthe same num bers in Figures 1 and 2. 34 is a large directional antenna;35 is the primary of an oscillation transformer, of which 36 is thesecondary; 37 is a variable condenser in the secondary receivingcircuit; 38. as shown, is a detector of the crystal type, but it may bea detector of any other suitable kind; 39 is acondenser.

In Figures 1, 2 and 3, instead of having the screen 6, the cathode raysmay impinge upon the end surface of the tube as shown in Figure 7.

In Figure 4, 40 is an evacuated tube, 41 is a directional coil insidethe tube, of the type shown in Figure 1; 42'is another directional coilinductively related to coil 41. with-its axis parallel to, or coincidentwith that of 41, and also contained in the tube; 43 is a filament whichcan be heated, or other source of ionization: 44 is a variable condenserconnected with coils 41 and 42; 45 is a variable condenser connectedwith coil 42 and filament 43; 46 is a battery for heating filament 43;47 is a variable resistance for regulating the current in filament 43;48 is a battery for energizing the circuit containing coil 41, filament43 and the primary 49, of a transformer. 50 is the secondary of thistransformer. 51 and 52 are coils and 53 is. a filament, or othersource'of ionization, contained in the tube 40, and similar,respectively, to coils 41 and 42 and filament 43. 54 and are variablecondensers. 56 is a battery and 57 a variable resistance, in circuitwith filament 53. 58 is a battery for energizing the circuit containingcoil 51, filament .53, and galvanon'ieter 59, which latter indicates thestrength of the received signals after amplification by theabove-described system.

In Figure 5, 60 is a directional loop antenna; (ll is a variablecondenser and 62 is a variable inductance. 63 is a filament; (.34 is agrid; and 65 is a plate, all three contained in a vacuum tube or bulb;66 is a battery for heating the filament 21; 67 is resistance torregulating the current passing through the filament; 68 is a battery forsupplying current to the plate circuit, which also comprises theprimary, 69, of a transformer. the secondary of which is 70. 71 is afilament; 72 is a grid, and 73 a plate; all three contained ina vacuumtube. 74 is a battery for heating the filament 71, and 75 is a variableresistance for regulating the current through the filament. 76 is abattery in circuit with the filament 71, the'plate 73, and thegalvanometer 77, which latter indicates the strength of the receivedsignals after amplification by the above receiving system.

In Figure 6, 80 and 81 represent directional loop antennae, whoseposition relative to each other is adjustable, but which are here shownat right angles to each other. Pre'autions should be taken to avoidmutual interference. ceiving apparatus such, for instance, as shown inFigures 1 to 5, but the details of which are omitted here for the sakeof convenience. 84 and 85 are sensitive galvanometers of any suitabletype. 86 and '87 are mirrors attached to the movin or indicating part ofthe galvanometers, 86 being shown with a horizontal suspension and 87with a vertical suspension, for purposes of illustration. 88 is a light,or source of illumination, of any convenient kind, the reflections ofwhich from the galvanometer mirrors indicate their movements. 89 is ascreen on which the reflections of the light 88 are thrown. 90 and-91are scales marked on the screen and here shown at right angles to eachother: but the angle between these scales may be any found mostsuitable. 92 and 93 are spots of light, being the reflections of thelight 88 from he galvanometer mirrors. Vhen bot-h mirrors are in theirnormal positions, that is to say, when no current is passing through thegalvanometers, the spots of light will beat the zero point at theintersection of the scales, but when current flows through one or both82 and 83 represent radio re-' galvanometers, the spot of lightcorrespondmg to that galvanometer, will move away from the zero pointalong its respective scale. In this figure, the spot of light 92 fromthe galvanometer mirror 86 is shown at some distance from the zeropoint, While the spot-of light 93 from the galvanometer mirror 87 isshown at the zero point.

In Figure 7, 94 and 95 are directional tube units on my system; 96 is anelement, such as a rod, connecting these two tubes, by which the can beturned in any desired direction. he tubes can be set at any desiredangle with each other, but are here.

shown at right angles. They should be far enough apart to avoid mutualinterference. 97 and 98 represent radio receivin apparatus such, forinstance, as shown in igures 1 and 4. 99, 100,101 and 102 are electrodesin a cathode-ray tube connected in pairs with the radio receivingapparatus 97 and 98. 103 is an induction or spark coil. 104 is a cathodera tube. 105 is an anode and 106 is a catho e in the tube and connectedwith the spark coil. 107 is a diaphragm with a small opening whichpermits a beam or pencil of cathode rays to pass through. 108rep-resents the cathode rays which have passed through the diaphragmopening. 109 is the end surface of the tube, composed of such materialas will show a spot or line of light where thebeam of cathode raysimpinges. It may also be a screen, composed of mica or some othersuitable material, as shown in Figures 1, 2 and 3. 110 is a line oflight produced by the movement of the beam of cathode rays. lightproduced when the beam of rays is at rest in its normal position. Thevarying electrification of the electrodes 99, 100, 101 and 102, causedby the varying amounts of radiant energy effectively received by thedirectional tubes 94 and 95, cause the beam of cathode-rays to move inone direction or the other from its normal position and so vary the formand dimensions of the lines of light on the screen 109. r

In Figure 8, 112 and 113 are directional loop antennae which can bemoved independently of each other, and which are far enough apart toprevent disturbing mutual interference. 114 and 115 represent radioreceiving apparatus connected, respectively, with the directional loops112 and 113, and which may be of any suitable kind such, for instance,as shown in Figures 1 to 5 inclusive. 116 and 117 are sensitivegalvonometers of any suitable type. 118 and 119 are mirrors attached tothe needles or other moving parts of the galvanometers. and suspended sothat spots of light reflected from them will travel in different pathswhen thrown on the screen 121. 120 is a light or source of illuminationof any suitable kind, which is reflected from the galvanometer 111 isthe spot of mirrors onto the screen 121. 122 and 123 represent lines oflight caused by the rapid movement to and fro of the galvanometermirrors 118 and 119, respectively. This movement of the galvanometermirrors is caused by the electromagnetic waves received on the loopantennae 112 and 113, respectively, as modified by the radio receivingapparatus 114 and 115. I may also use types of galvanometers such asthose used in Figure 6, which have a steady deflection instead of arapid vibration of the movable members.

In Figure 9, M and N represent transmitting stations whose position onthe chart or map is fixed. A and B re resent different positions of amovable receiving station on an aircraft, or boat, or other moving body.145 and 146 are directional loop antennae, directional tubes or otherapparatus which receives varying amounts of radiant energy dependingupon its direction with reference to the transmitting station. When themoving body is in position A, these direction finders are turned untilone gets the maximum cited; (or the minimum efiect), from onetransmitting station and the other gets the maximum effect (or theminimum effect) from the second transmitting station. The direction ofthe transmitting stations from the movin body is thus determined at anyinstant an the exact position of the moving body can be at once fixed onthe. chart or map if the compass bearing of at least one of thetransmitting stations is also known. After any interval of time,observations can again be made,-and a second position of the movingbody, such as at B, can be fixed. The course A-B and the distancetraveled can then be readily ascertained.

In cases where neitherthe magnetic nor gyroscopic compass can be reliedupon, and where the heavenly bodies are obscured so that it isimpossible to find the compass bearing of either of two transmittingstations, the position of the moving body can nevertheless be determinedby getting the direction of a third transmitting station, such as P,whose position on the map is fixed. The direction of P is determined bymeans of a third direction finder, such as 147, similar to 145 and 146,which is turned until the maximum effect (or the minimum efiect) isobtained from station I, and the latters direction is then notedsimultaneously with the directions of the other two stations M and N.The position of the receiving station can then be found by calculationor with suitable instruments. To ascertain conveniently and quickly theposition of the receiving station on the map or chart, suitablemathematical tables and mechanical aids can be used.

Figure 10 shows a system for obtaining avoid disturbing mutualinterference.

' the directions of three transmitting stations simultaneously. 124, 125and 126 are directional tubes, but there mayalso be used directionalloop antennae, or other direction finders which can be movedindependently of each other and are far enough apart t 12 128 and 129represent radio receiving apparatus of any suitable type, such as shown,for instance, in Figures 1 to 5, inclusive. 130,- 131 and 132 aresensitive galvanometers of any suitable type. 133, 134 and 135 aremirrors attached to the movable indicating parts of these galvanometers,respectively. 136, 137 and 138 are lights of any suitable type, toberefiected from the galvanometer IIllITOIS onto the screens 139, 140and 141, respectively. 142, 143 and 144 are lines of light produced bythe movement of the galvanometer mirrors, the extent of the deflectionof the galvanometer mirrors being shown byscales on the screens. Insteadof a line of light as here shown, caused by the rapid to and fro motionof the galvanometer needle or reed or other moving part, there may be aspot of light in a steady position produced by the steady deflection ofthe galvanometer mirror, where such a type of galvanometer is used.

In the forms of'my invention shown in Figures 1, 4, 7 and 10, I employdirectional receiving means which I have described fully in myco-pending application, Serial No. 308,978, filed July 7, 1919. InFigure 1 there is shown aslngle unit, in Figure 4 there are two units inthe same evacuated tube, in Figure 7 there are shown two separate tubes,each of which may contain one or more units, and in Figure 10 there areshown three separate tubes, each of which may contain one or more units.I have found that when the lanes of the coils in the tubes are in thedlrection of the transmitting station, or, in other words, when the axesof the coils are at right angles to a line joining the transmitting andreceiving stations, the received signals are at a maximum. The tubeswith the coils are therefore turned until the maximum 'effects areobserved on the indicating apparatus, and the direction of thetransmitting station is at once determined. Besides acting as'directionfinders, my tubes, with the accompanying apparatus, also perform thefunction of electrical wave or oscillation detectors.

In the forms of my invention shown in Figures 1, 2 and 3, the variationsof the received current change the electrical condition of the terminals7 and 8, and thereby cause deflections of the pencil or beam of cathoderayspassing along the tube 1, through the dia hragm 5.

The rapidly-a ternating variations in the electrification of theterminals 7 and 8 are followed by movements of the pencil of rays. Atthe end of the tube the pencil of rays falls upon a mica screen or someother suitable surface, and when at rest, it makes a spot of lightthere. When under the influence of the alternating electrification ofthe terminals 7 and 8, the pencil or beam of rays moves to and fro, andtraces a line of light on the screen. The greater the electrification ofthe terminals, the greater the amplitude of the movements of the beam ofFigure 7, I employ two direction-finding tubes, which are independent ofeach other. The energy received by the directional coils in one of them,94, acting through the rest of the apparatus, indicated at 97, variesthe electrical condition of the electrodes 99 and 100, which are 180degrees apart, and so changes the direction of thebeam of rays 108. Whenthese changes follow each other rapidly, a line of light appears on thescreen. The energy received by the directional coils in the other tube,95, acting through the rest of the radio apparatus indicated at 98,varies the electrical condition of the electrodes 101 and 102, which are180 degrees apart, and 90 degrees from electrodes 99 and 100. Thesevariations in electrodes 101 and 102 deflect the beam of rays at rightangles to the deflections caused by electrodes 99 and 100. The resultantdlrection of the beam of rays will depend upon the relative strength ofthe electrification of the electrodes, and so will the form anddimensions of the figure of light traced on the screen 109. When theelectrification of one pair of electrodes, for instance, 99 and 100, isat a maximum, and the electrification of the other pair, 101 and 102, isat a minimum, the beam of rays will vibrate in a plane throughthe-electrodes 99 and 100, and a line of light, such as shown at 110,will be traced on the screen. This state of affairs will indicate thatthe tube 9 1 is receiving the maximum effect from the 'incomin radiantenerg and the tube 95 the mimmum effect. s these tubes have been set sothat the axes of their enclosed coils are at right angles to each other,the direction of the distant transmitting station is at once determined.By this system, any deviation from the maximum or minimum position thanwhen only one tube is used.

Instead 'of using two of m directional tubes with my cathode-rayindicator, I may employ two directional loop antennae, or two largedirectional antennae, in a similar manner to that shown with onedirectional loop and one large directional antenna, in Figures 2 and 3,respectively.

In the forms of my invention shown in Figures 4, 5, 6 and 8, sensitivegalvanometers indicate the strength of the received signals. In somecases, it is preferable to amplify the received oscillations in order tocause the galvanometers to show great enough deflections, and Itherefore provide amplifyingzmeans, as shown. In the form shown in igure4, the amplification is secured by two units of my directional-tubesystem, fully described in my said co-pending application, and in theform shown in Figure 5, the amplification is obtained by means of anordinary vacuum tube amphfier. With some forms of galvanometer, such,for instance, as those having a vibrating reed capable of being tuned toa definite fre uency, amplification Is not essential, and nee not beemployed.

In the form of my invention shown in Figure 6, I employ two directionalloops at right angles to each other, so that when one is in the positionfor maximum effect, the other is in the position for minimum effect. Mindicating means consists of sensitive galvanometers, one of which isactuated, through suitable receivin apparatus, by the effective energyreceived y one of the loops, and the other one is actuated by theeffective energy received by the other loop. For purposes of convenienceI use a single screen for receiving the spots of light reflected fromboth lvanometer mirrors, and I dispose the mirrors so that the movementsof the beams of light from them are in different planes, and can beclearl distinguished on the screen. I have here s own the spots of lightmoving at right angles to each other, but they may make any convenientangle. Instead of the directional loops I may use my direction-findintubes arranged as shown in Figure 7. fie arrangement shown in Figure 6is particularly useful for the purpose of determining the direction of asingle transmitting station more accurate- 1 than can be done with asingle loop, but the loops can be adjustable so as to make any anglewith each other and can then be used to determine the direction of twotransmitting stations simultaneously, provided proper precautions aretaken to avoid mutual interference between the loops.

In Figure 8 is shown a modification of my system, embodying a preferablearrangement for receiving electromagnetic waves from two transmittingstations simultaneously and determining their res ective directions. Iuse two separate directional loops, which can be adjusted independentlyof each other.

Each one actuates a sensitive galvanometer or other suitable indicatingapparatus, and the reflected light from these two galvanometer mirrorsis thrown on the same screen. The galvanometer mirrors are so suspendedthat the beams of light from them move in different planes, and areshown in different lines on the screen. I may employ a form ofgalvanometer in which the light is reflected rom a member which vibratesunder the influence of the incoming currents or oscillations, so thatthe beam of light traces a line upon the screen, the len h of this lineindicating the strength of t e received current, and hence the effectiveenerg received in any position of the directiona loop. Each receivingunit should preferably be tuned to the wave length of the transmittingstation, and where a tuned vibrating reed is used in the galvanometer,this reed should be tuned to the spark or group frequency of itscorrespondlng transmitting station. The loops s ould also be placed soas to avoid mutual interference with each other. In operatin thissystem, the loops should be turned unti the maximum deflection for eachunit is observed on the screen. At this instant, the direction of therespective loops is noted, and, if necessary, transferred to a chart ormap, and the position of the receivin station can be determined, asshown in igure 9, provided the compass bearing of at least one of thetransmitting stations is also determined at the same time by thedirection finder. If, however, at the receiving station the magneticcompass and the gyroscopic compass or any other means of showing thecompass bearing are not operative, and if the heavenly bodies areinvisible, it will be necessary to know the direction of a thirdtransmitting station in order to fix the position of the receivingstation.

In Figure 10, I have shown the means for accomplishing this object. Ithere have three direction finding units, one for each of thetransmitting stations. The direction finding member may be either one ofmy direction finding tubes, or a directional loop antenna, or any othersuitable means. The indicat ing means may be either galvanometers,cathode-ray tubes, or other suitable means for showin the strength ofthe received energy visual y. Each receiving system is preferably tunedto the wave length of its corresponding transmitting station, and wherea tuned indicating apparatus is employed, the latter is also tuned tothe spark or group frequency of the corresponding transmitting station.The directional tubes or loops and other receiving apparatus are soarranged as to avoid mutual interference.

The dimensions and characteristics of the loops, coils and otherapparatus, and the values of the electrical quantities of the variousarts of my system are so chosen as to obtain the best results in eachcase. In general, I do not confine myself to the exact constructions andarrangements herein described, but I may also employ other means withinthe scope of my invention, but what I claim and'desire to secure byLetters Patent is:

1. In a radio receiving system, the combination with directionalreceiving means enclosed in an evacuated tube, of a visual indicator ofthe strength of the received signals.

2. In a system for receiving radiant en ergy, the combination withdetecting and directional receiving means enclosed in an evacuatedvessel, of visual means for indicating the strength of the receivedsignals.

3. n a radio receiving system, the combination with a plurality ofevacuated tubes containing directional receivingcoils, of visual meansfor indicating the effective radiant energy received on said coils.

4. A radio receiving system having two directionalreveiving units,each-of said units consisting of coils and a filament contained in anevacuated tube, the axes of the two sets of said coils being at rightangles to each other.

Siglned b me, this 23rd. day of Jul 1919.. RE ERICK s. MoCULLO G

